1. Field of the Invention
The present invention relates to a method for transmitting video-audio signals by power lines. In particular, the present invention relates to a power line transmission method that is not interfered by noise of the public power system and an apparatus thereof.
2. Description of Related Art
As display technology and audio play technology has been developed well, people enjoy high quality image and audio. Therefore, the standards of display signal interfaces for high quality image and audio and compression standards of audio signals are established. The video and audio signal interface standards make people enjoy vivid display images and high quality of multi-channel audio. However, display screens and audio players of home theaters or any related devices usually have complicated power lines and signal transmission cables locating out of the devices, such that the living environment becomes a mass.
As shown in FIG. 1, home network 10 includes at least one set of external power line 12 having a plurality of sockets 14. The home network 10 includes a modem 20 connected with an internet 22, a DVD player 30, a VCD player 40, a DVD video camera 50, a computer 60, an audio player 70 and a display screen 80, etc. In the future, air conditioners, refrigerators, telephones, or other home equipments may be connected with the external power line 12 to build up an integrated home network 10. By using remote controllers, the apparatuses connected with the home network 10 are controllable.
By utilizing power line network technology, the quality of signals becomes worse due to the interference by noise of the public power system. Therefore, the signals modulated on the public power signal are interfered by the noise. High video and audio quality which are paid more attention by people nowadays require precise signal transmission quality. Consequently, if the signal transmission quality is affected, it results in troubles for people while applying it.